PBX3 and leukemia: We also measured the Bcat1 mRNA levels in WT, P2x1-null, Pbx3-overexpressing WT or P2x1-null leukemia cells and showed that the Bcat1 mRNA level was significantly downregulated in P2x1-null AML cells, while increased in Pbx3-overexpressing leukemic cells (Fig. S4E).